1. Technical Field
The present invention relates to a robot control device, a robot, and a robot system.
2. Related Art
Robots having a robot arm constituted by links of multiple joints are known. For example a hand or the like as an end effector is mounted on a tip portion of the robot arm. The robots are utilized for a number of apparatuses, such as assembling apparatuses.
In such robots, the robot arm vibrates when the robot arm is moved and stopped. While the robot arm is vibrating, the hand mounted on the tip portion of the robot arm also vibrates. Since it is difficult for the hand to perform the work of gripping a workpiece while the hand is vibrating, it is necessary to wait for the vibration of the hand to stop.
Thus, a method of shortening the time taken for the hand to vibrate in order to raise the productivity of a robot is disclosed in JP-A-2005-242794. Although the robot disclosed in JP-A-2005-242794 is a scalar robot having a base and a robot arm linked to the base, according to this, an angle sensor that detects the rotational angle of the robot arm is arranged at an actuator of the robot arm. Moreover, an angular velocity sensor that detects the vibration of the robot arm is arranged at the robot arm. A low-frequency component of the angle sensor is extracted using a low-pass filter, and a high-frequency component of the output of the angular velocity sensor is extracted using a high-pass filter. Next, the operation of the robot arm is detected by composing the output of the angle sensor and the output of the angular velocity sensor. The vibration of the robot arm is suppressed by controlling the robot arm in response to the operation of the robot arm.
The method described in JP-A-2005-242794 is a method that is effective as a method of attenuating the vibration of the robot arm linked to the base that stands still.
However, in double-arm robots having a base, a trunk rotatably linked to the base, and two robot arms rotatably linked to the trunk, not only the robot arms but also the trunk vibrate. Accordingly, the double-arm robots as mentioned above has a problem in that it is difficult to attenuate the vibration of the robot arm because the vibration of the trunk is transmitted to the robot arms even if the vibration of the robot arms is attenuated using the method described in JP-A-2005-242794.